Abstract: A device for creating an angular biasing force for the roller tube of a security shade, which roller tube is mounted to a fixed structure of a vehicle. The device comprises an element attached to the fixed structure of the vehicle and a plurality of force units, each including a torsion spring exerting a biasing force between the structure and the roller tube, wherein the torsion springs each have a first inner end associated with the fixed structure and a second outer end associated with the roller tube so the torsion biasing force of each spring is in a direction from the fixed structure to the roller tube. The total angular force of the device is the sum of the biasing forces of all of the torsion spring force units when the units are connected in parallel. When connected in series, the magnitude of angular rotation is the sum of the angle of rotation of all units.